1. Field of the Invention
The present invention relates to methods and apparatus for promoting heat transfer. More particularly, the present invention relates to methods and apparatus for promoting an increase of convection heat transfer in systems employing electronic components.
2. Description of Related Art
As integrated circuit packages and devices have become smaller, with shorter circuit traces and increased internal signal speeds, greater power density has resulted, causing increased heating of the devices and a need for improved heat sinking and better thermal management.
A few methods and/or apparatus are commonly employed for providing such thermal management. Some of those include: heat conduction, where through a material, such as aluminum, heat flows from a warmer temperature to a cooler temperature; natural convection, which relies on airflow for cooling without any external forces applied to the air; forced convection where fans or blowers move air in a direction parallel to the surface of an element from which heat is being removed; and impingement cooling where the air is blown at the element to be cooled in a direction perpendicular to its surface.
Although not required, often, heat sinks are provided with each of the above methods and/or apparatus to improve the removal of heat from the element. Commonly, cooling fins or vanes are employed with the heat sinks for this purpose. Each of the indicated methods and/or apparatus for cooling has a disadvantage when implemented with today""s ultra dense and sensitive integrated circuits and/or electronic devices. The heat produced by current integrated circuits can reach staggering temperature levels. Accordingly, a conventional heat sink, which relies solely upon convection heat transfer, is incapable of property cooling, and therefore, maintaining such integrated circuits at an acceptable operational temperature.
Forced convection and impingement cooling are capable of overcoming the deficiency of natural convection heat transfer. Specifically, each of forced convection and impingement cooling implements an air moving device to increase the mass flow of air across the element. This requires the installation of a fan and a predetermined supply voltage for operating the fan. The larger the increase in mass flow of air that is desired, the higher capacity fan and/or the larger the supply voltage. However, even if the element is to be cooled with a minimally sized fan, which requires a very small supply voltage, the acoustic signature of the fan may disrupt the desired operational characteristics of the integrated circuit being cooled. In many situations such a disruption in the operational characteristics of the integrated circuit is unacceptable.
The present invention provides a novel method and apparatus to increase convection heat transfer in an electrical system. The increase in convection heat transfer is achieved by introducing a heat source in the vicinity of an element to be cooled, thereby increasing convection heat transfer, i.e. increasing the amount of airflow across the element.
In addition, according to the present invention, a novel method of manufacturing an apparatus to increase convection heat transfer in an electronic system is provided. The method of manufacture includes the use of an electronic device, which is. preferably cooled using a heat source and an optional heat sink. The heat source is used to increase the convection heat transfer.